Cwm Idwal

Mr. Roberts adds, “Darwin’s favourite place. This is looking down into Cwm Idwal in Snowdonia, which Darwin visited several times in the 1820s and in August 1831 just before he received the invite for the Beagle and in 1842 when he was studying glaciation.

“In 1831 Darwin studied the rocks, which are mostly Ordovician volcanics, but was a bit confused by them. He was on his own and wrote to Sedgwick for advice. In 1842 (halfway through writing his first draft on “his Theory”) he returned and found clear evidence of glaciation. To the right of the lake (Llyn Idwal) was an ice fall which Darwin called a vomitory. The dark cliffs on the left are Ordovician volcanics, which he thought were basalt.”

You may find Mr. Roberts’s article on Darwin’s fieldwork here, but you will not find it cheaply..

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Beautiful. I used to go there a lot and yomp up the odd mountain – one of the loveliest landscapes in the world. Snowdown may be impressive, but Tryfan and/or the Gwydrs are more of a workout and give cracking landscape – the latter, in particular, is like the surface of another planet.

This was taken in August 2007 while leading a trip for Harvard led by Andrew Berry. By the lake the weather was awful, but Andrew and I saw some blue sky so went over the tops - the Glyderau 1000metres to Plas y Brenin where Darwin stayed

For more see C:\newdarwin)\Geological Society - Rocks of ages.mht on Darwin’s 1842 glacial visit . You will see the boulders and the headwall of the cwm above the lake is where I took the photo